configureCallback

Set callback function and trigger condition for communication

Since R2021a

Syntax

configureCallback(t,"terminator",callbackFcn)

configureCallback(t,"byte",count,callbackFcn)

configureCallback(t,"off")

Description

configureCallback(t,"terminator",callbackFcn) sets the callback function callbackFcn to trigger whenever a terminator is available to be read from the client connected to the TCP/IP server t. The syntax sets the BytesAvailableFcnMode property of t to "terminator" and the BytesAvailableFcn property to callbackFcn.

Set the terminator character using configureTerminator.

configureCallback(t,"byte",count,callbackFcn) sets the callback function callbackFcn to trigger whenever a new count number of bytes are available to be read. The syntax sets the BytesAvailableFcnMode property of t to "byte", the BytesAvailableFcnCount property to count, and the BytesAvailableFcn property to callbackFcn.

configureCallback(t,"off") turns off callbacks. The syntax sets the BytesAvailableFcnMode property of t to "off".

Examples

Set TCP/IP Server Callback and Trigger to Terminator Mode

Create a callback function called readFcn and save it as a .m file in the current working directory.

function readFcn(src,~)
message = readline(src);
disp(message)
end

Create a TCP/IP server that listens for connections at localhost and port 4000.

server = tcpserver("localhost",4000)

server = 
  TCPServer with properties:

        ServerAddress: "127.0.0.1"
           ServerPort: 4000
            Connected: 0
        ClientAddress: ""
           ClientPort: []
    NumBytesAvailable: 0

  Show all properties, functions

Create a TCP/IP client to connect to your server object using tcpclient. You must specify the same IP address and port number you use to create server.

client = tcpclient("localhost",4000)

client = 
  tcpclient with properties:

              Address: 'localhost'
                 Port: 4000
    NumBytesAvailable: 0

  Show all properties, functions

Set the callback function readFcn to trigger when a terminator is available to be read in the server. The callback function readFcn reads and displays the message sent from the connected client.

configureCallback(server,"terminator",@readFcn)

View the properties to confirm the change.

server.BytesAvailableFcnMode

ans = 
"terminator"

server.BytesAvailableFcn

ans = function_handle with value:
    @readFcn

Write a string of ASCII data to the TCP/IP client. Since the client is connected to the server, this data is available in the server. When the server receives the data with a terminator from the client, server triggers its callback function, which displays the data.

writeline(client,"Hello, world!")

Hello, world!

Turn the callback off.

configureCallback(server,"off")

Verify that the callback is off.

server.BytesAvailableFcnMode

ans = 
"off"

Set TCP/IP Server Callback and Trigger to Byte Mode

Create a callback function called readByteFcn and save it as a .m file in the current working directory.

function readByteFcn(src,~)
data = read(src,src.NumBytesAvailable);
disp(data)
end

Create a TCP/IP server that listens for connections at localhost and port 4000.

server = tcpserver("localhost",4000)

server = 
  TCPServer with properties:

        ServerAddress: "127.0.0.1"
           ServerPort: 4000
            Connected: 0
        ClientAddress: ""
           ClientPort: []
    NumBytesAvailable: 0

  Show all properties, functions

Create a TCP/IP client to connect to your server object using tcpclient. You must specify the same IP address and port number you use to create server.

client = tcpclient("localhost",4000)

client = 
  tcpclient with properties:

              Address: 'localhost'
                 Port: 4000
    NumBytesAvailable: 0

  Show all properties, functions

Set the callback function readByteFcn to trigger when five bytes of new data are available to be read in the server. The callback function readByteFcn reads and displays all the data sent from the connected client.

configureCallback(server,"byte",5,@readByteFcn)

View the properties to confirm the change.

server.BytesAvailableFcnMode

ans = 
"byte"

server.BytesAvailableFcnCount

ans = 5

server.BytesAvailableFcn

ans = function_handle with value:
    @readByteFcn

Write five bytes of data to the TCP/IP client. Since the client is connected to the server, this data is available in the server. When the server receives the five bytes of data from the client, server triggers its callback function, which displays the data.

write(client,1:5,"uint8")

1 2 3 4 5

Turn the callback off.

configureCallback(server,"off")

Verify that the callback is off.

server.BytesAvailableFcnMode

ans = 
"off"

Input Arguments

t — TCP/IP server

tcpserver object

TCP/IP server, specified as a tcpserver object.

Example: configureCallback(t,"byte",128,@callbackFcn) sets the callbackFcn callback to trigger each time 128 bytes of new data are available to be read from the TCP/IP server t.

count — Number of bytes of data to trigger callback

positive integer value

Number of bytes of available data to trigger the callback, specified as a positive integer value. Set the BytesAvailableFcnCount property using this argument.

Example: configureCallback(t,"byte",128,@callbackFcn) sets the callbackFcn callback to trigger each time 128 bytes of new data are available to be read.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

callbackFcn — Callback function to run when trigger condition is met

function handle

Callback function to run when trigger condition is met, specified as a function handle. The function handle can be a named function handle or an anonymous function with input arguments. Set the BytesAvailableFcn property using this argument.

Example: configureCallback(t,"terminator",@callbackFcn) sets the callbackFcn callback to trigger when a terminator is available to be read.

Data Types: function_handle

Version History

Introduced in R2021a